Elliptical hole pockets in the Fermi surfaces of unhydrated and hydrated sodium cobalt oxides

Authors

J Laverock, University of Bristol
S B. Dugdale, University of Bristol
J A. Duffy, University of Warwick
J Wooldridge, University of Warwick
G Balakrishnan, University of Warwick
M R. Lees, University of Warwick
G.-q Zheng, Okayama University
Dapeng Chen, University of WollongongFollow
C T. Lin, University Of Wollongong
Y Sakurai, Japan Synchrotron Radiation Research Institute

RIS ID

41244

Publication Details

Laverock, J., Dugdale, S. B., Duffy, J. A., Wooldridge, J., Balakrishnan, G., Lees, M. R., Zheng, G., Chen, D., Lin, C. T. & Sakurai, Y. (2007). Elliptical hole pockets in the Fermi surfaces of unhydrated and hydrated sodium cobalt oxides. Physical Review B: Condensed Matter and Materials Physics, 76 (5), 052509-1-052509-4.

Abstract

The surprise discovery of superconductivity below 5 K in sodium cobalt oxides when hydrated with water has caught the attention of experimentalists and theorists alike. Most explanations for its occurence have focused heavily on the properties of some small elliptically shaped pockets predicted to be the electronically dominant Fermi surface sheet, but direct attempts to look for them have instead cast serious doubts over their existence. Here we present evidence that these pockets do indeed exist, based on bulk measurements of the electron momentum distribution in unhydrated and hydrated sodium cobalt oxides using the technique of x-ray Compton scattering.